The present disclosure relates to a light detection apparatus that detects light passed through a filter.
Conventionally, various image readout apparatuses for reading out fluorescent images by illuminating, with excitation light, a subject to be examined, such as a gel support body including fluorescence-labeled protein, peptide, nucleic acid and the like or a storable phosphor sheet from which a fluorescent-material-labeled substance derived from an organism has been removed after the substance was placed in close contact therewith, and by detecting fluorescence generated by illumination with the excitation light have been proposed.
Specifically, for example, Japanese Unexamined Patent Publication No. 2001-296395 (Patent Document 1) proposes an image readout apparatus that can read out fluorescent images of both a fluorescence-labeled gel support body and a storable phosphor sheet. In a case where fluorescent images of plural kinds of subjects to be examined are read out as in the image readout apparatus disclosed in Patent Document 1, the subjects to be examined need to be illuminated with excitation light having wavelengths corresponding to the kinds of the subjects to be examined, and fluorescence having different wavelengths needs to be detected, respectively.
Meanwhile, in the aforementioned image readout apparatuses, an excitation light cut filter needs to be provided on an optical path of fluorescence to prevent unwanted excitation light from entering a detector for detecting fluorescence, such as a photomultiplier. Further, in a case where the subjects to be examined are illuminated with excitation light having wavelengths corresponding to the subjects to be examined, excitation light cut filters corresponding to the wavelengths of the excitation light are needed respectively.
The image readout apparatus disclosed in Patent Document 1 proposed a structure using a dichroic mirror that separates fluorescence of different wavelength to orthogonal directions, and in which an excitation light cut filter and a detector are placed on each of a transmission optical path and a reflection optical path of fluorescence of the dichroic mirror.